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Total Categories: 6
Repetitive DNA sequences constitute less than one-tenth of the human genome.
Answer: False
Repetitive DNA sequences constitute a substantial portion of the human genome, exceeding two-thirds.
All repetitive DNA sequences are considered non-functional 'junk DNA'.
Answer: False
While some repetitive sequences were historically viewed as non-functional 'junk DNA', research increasingly reveals potential functions in genome structure and regulation.
Barbara McClintock first observed DNA transposition in the 1970s.
Answer: False
Barbara McClintock made her foundational observations regarding DNA transposition in the 1950s.
The term 'repeated sequence' was first introduced in scientific literature in 1968 by Roy John Britten and D.E. Kohne.
Answer: True
Roy John Britten and D.E. Kohne first introduced the term 'repeated sequence' in 1968, based on their DNA reassociation experiments.
Transposable elements (TEs) are estimated to comprise about 45% of the human genome.
Answer: True
Transposable elements constitute approximately 45% of the human genome, highlighting their significant impact.
What proportion of the human genome is estimated to be composed of repetitive elements?
Answer: Exceeding two-thirds
Repetitive elements constitute a substantial portion of the human genome, estimated to be over two-thirds.
Who is credited with first observing DNA transposition and laying groundwork for understanding repetitive elements?
Answer: Barbara McClintock
Barbara McClintock is credited with the first observations of DNA transposition, providing foundational insights into repetitive elements.
In what decade did Barbara McClintock make her foundational observations regarding DNA transposition?
Answer: 1950s
Barbara McClintock made her foundational observations regarding DNA transposition in the 1950s.
The term 'repeated sequence' was first introduced in scientific literature in which year?
Answer: 1968
The term 'repeated sequence' was first introduced in scientific literature in 1968 by Roy John Britten and D.E. Kohne.
Tandem repeats are characterized by being scattered across different locations throughout the genome.
Answer: False
Tandem repeats are sequences that are directly adjacent to each other, forming arrays, whereas interspersed repeats are scattered across different locations throughout the genome.
Minisatellite and microsatellite repeats gained significant research interest in the 1990s primarily due to their role in gene regulation.
Answer: False
Minisatellite and microsatellite repeats gained significant research interest in the 1990s primarily due to their applications in DNA-based forensics and molecular ecology, rather than gene regulation.
Microsatellites, also known as short tandem repeats (STRs), have repeat units typically ranging from 10 to 60 nucleotides.
Answer: False
Microsatellites, or short tandem repeats (STRs), have repeat units typically ranging from 2 to 10 nucleotides, while minisatellites have repeat units of 10 to 60 nucleotides.
Minisatellites primarily function as genetic markers in DNA fingerprinting due to their high variability.
Answer: False
Minisatellites primarily serve as hotspots for homologous recombination, while microsatellites (STRs) are widely used as genetic markers in DNA fingerprinting due to their high variability.
Interspersed repeats are clustered together in specific genomic locations.
Answer: False
Interspersed repeats are dispersed across various genomic locations, unlike tandem repeats which are clustered.
Transposable elements (TEs) are mobile DNA sequences that can move to different locations within the genome.
Answer: True
Transposable elements (TEs), often called 'jumping genes,' are mobile DNA sequences capable of relocating within the genome.
Retrotransposons move by directly copying themselves into new DNA locations without an RNA intermediate.
Answer: False
Retrotransposons move via an RNA intermediate, involving transcription into RNA, reverse transcription into DNA, and subsequent integration.
LINEs (Long Interspersed Nuclear Elements) are typically shorter than SINEs (Short Interspersed Nuclear Elements).
Answer: False
LINEs are generally longer (3-7 kb) than SINEs (100-300 bp).
Direct repeats involve sequences repeated in opposite directions.
Answer: False
Direct repeats involve sequences repeated in the same direction, whereas inverted repeats are repeated in the opposite direction.
A palindromic repeat occurs when an inverted repeat sequence is immediately adjacent to its reverse complement.
Answer: True
A palindromic repeat is defined as an inverted repeat sequence immediately adjacent to its reverse complement.
Microsatellites are valuable genetic markers despite challenges in accurate sequencing.
Answer: True
Microsatellites are valuable genetic markers for applications like DNA fingerprinting due to their high polymorphism, despite sequencing challenges.
Satellite DNA is primarily found in gene coding regions and is crucial for protein synthesis.
Answer: False
Satellite DNA is primarily found in non-coding regions, such as centromeres and pericentromeres, and plays roles in chromosome structure and stability.
Inverted repeats can form stem-loop structures in RNA molecules.
Answer: True
Inverted repeats can fold to form secondary structures, such as stem-loops in RNA and cruciforms in DNA.
LINEs rely on SINEs for the proteins required for their transposition.
Answer: False
SINEs rely on LINEs for the proteins required for their transposition, as SINEs do not encode these proteins themselves.
How are repeated sequences primarily categorized based on their genomic arrangement?
Answer: Tandem repeats and interspersed repeats
Repeated sequences are primarily categorized based on their genomic arrangement into tandem repeats (adjacent) and interspersed repeats (scattered).
What field saw increased interest in minisatellite and microsatellite repeats during the 1990s?
Answer: DNA-based forensics and molecular ecology
The 1990s saw increased research interest in minisatellite and microsatellite repeats due to their significance in DNA-based forensics and molecular ecology.
Which type of tandem repeat has repeat units typically measuring 2-10 nucleotides?
Answer: Short tandem repeats (STRs)
Short tandem repeats (STRs), also known as microsatellites, are characterized by repeat units typically ranging from 2 to 10 nucleotides.
What distinguishes interspersed repeats from tandem repeats?
Answer: Interspersed repeats are scattered across the genome, not clustered.
Interspersed repeats are dispersed throughout the genome, unlike tandem repeats which are clustered together.
What are transposable elements (TEs) commonly referred to as?
Answer: Jumping genes
Transposable elements (TEs) are commonly referred to as 'jumping genes' due to their ability to move within the genome.
Which class of retrotransposons moves via an RNA intermediate and is characterized by Long Terminal Repeats (LTRs)?
Answer: LTR retrotransposons
LTR retrotransposons are a class of retrotransposons that move via an RNA intermediate and are characterized by Long Terminal Repeats (LTRs).
What is the typical length range for Short Interspersed Nuclear Elements (SINEs)?
Answer: 100 to 300 base pairs
Short Interspersed Nuclear Elements (SINEs) are typically between 100 to 300 base pairs in length.
What makes microsatellites valuable as genetic markers?
Answer: Their high degree of polymorphism (variation)
Microsatellites are valuable genetic markers due to their high degree of polymorphism (variation) among individuals.
What is the significance of inverted repeats in nucleic acids?
Answer: They can fold into stem-loop or cruciform structures.
Inverted repeats can fold to form secondary structures, such as stem-loops in RNA and cruciforms in DNA.
Telomeres and centromeres are examples of genomic structures maintained by specific repeated DNA sequences.
Answer: True
Specific repeated DNA sequences are crucial for maintaining the integrity of telomeres, which protect chromosome ends, and centromeres, which are essential for chromosome segregation.
Full eukaryotic genome sequencing in the 2000s helped identify regulatory elements encoded by repetitive regions.
Answer: True
Genome sequencing advancements in the 2000s enabled the identification of regulatory elements, including promoters and enhancers, many of which are encoded within repetitive regions.
Telomeres are composed of tandem repeats of the sequence TTAGGG and protect chromosome ends.
Answer: True
Telomeres, located at chromosome ends, are primarily composed of TTAGGG tandem repeats that protect the DNA ends from degradation.
Human centromeres are primarily composed of a 177 base pair tandem repeat known as the alpha-satellite repeat.
Answer: True
Human centromeres are predominantly formed by a specific 177 base pair tandem repeat sequence called the alpha-satellite repeat.
Pericentromeric heterochromatin contains only alpha-satellite DNA subfamilies.
Answer: False
Pericentromeric heterochromatin contains a mix of satellite DNA subfamilies, including alpha-, beta-, and gamma-satellites, as well as other repeat types.
Epigenetic modifications like DNA methylation are not involved in regulating transposable elements.
Answer: False
Epigenetic modifications, such as DNA methylation and histone modifications, are key mechanisms cells use to regulate transposable elements.
Intrachromosomal recombination involves sequences on different chromosomes.
Answer: False
Intrachromosomal recombination occurs between repeated sequences located on the same chromosome, often facilitating DNA repair.
Which critical genome structures are maintained by certain repeated DNA sequences?
Answer: Telomeres and centromeres
Telomeres and centromeres are critical genome structures whose integrity is maintained by specific repeated DNA sequences.
What technological advancement in the 2000s significantly aided the study of repetitive sequences by revealing regulatory elements?
Answer: Full eukaryotic genome sequencing
Full eukaryotic genome sequencing in the 2000s enabled the identification of regulatory elements encoded by repetitive regions.
What is a primary biological function attributed to minisatellites?
Answer: Serving as hotspots for homologous recombination
Minisatellites often serve as hotspots for homologous recombination during meiosis, a process vital for genetic diversity and DNA repair.
The sequence TTAGGG is a type of tandem repeat primarily found in which chromosomal region?
Answer: Telomeres
The TTAGGG sequence is a tandem repeat primarily found in telomeres, the protective caps at the ends of chromosomes.
What specific tandem repeat sequence is characteristic of human centromeres?
Answer: Alpha-satellite repeat
Human centromeres are primarily composed of a specific 177 base pair tandem repeat known as the alpha-satellite repeat.
Which of the following is NOT mentioned as being part of pericentromeric heterochromatin?
Answer: LINE sequences
Pericentromeric heterochromatin is described as containing various satellite DNA subfamilies and HSATII repeats, but not LINE sequences.
What role do repeat sequences play in DNA repair mechanisms?
Answer: They serve as templates for homologous recombination.
Repeat sequences can serve as templates for homologous recombination, a key DNA repair mechanism.
Trinucleotide repeat expansions are commonly associated with neurological diseases like Huntington's disease.
Answer: True
Trinucleotide repeat expansions are frequently associated with neurological disorders, including Huntington's disease.
Fragile X syndrome is caused by an expansion of the CAG trinucleotide repeat.
Answer: False
Fragile X syndrome is caused by an expansion of the CCG trinucleotide repeat in the FMR1 gene.
In Huntington's disease, the expanded repeat leads to a shortened polyglutamine domain in the huntingtin protein.
Answer: False
In Huntington's disease, the expanded repeat leads to an elongated polyglutamine domain in the huntingtin protein.
Friedreich's Ataxia is linked to an expansion of the GAA trinucleotide repeat within the frataxin gene.
Answer: True
Friedreich's Ataxia is associated with GAA trinucleotide repeat expansion within the frataxin gene, leading to frataxin deficiency.
Myotonic dystrophy type 1 (DM1) is caused by a CCTG repeat expansion in the ZNF9 gene.
Answer: False
Myotonic dystrophy type 1 (DM1) is caused by a CTG repeat expansion in the DMPK gene; a CCTG repeat expansion in ZNF9 is associated with DM2.
ALS and Frontotemporal Dementia can be associated with a GGGGCC repeat expansion in the C9orf72 gene.
Answer: True
Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD) are associated with GGGGCC repeat expansion in the C9orf72 gene.
The phenomenon of anticipation, where diseases worsen over generations, can be driven by repeat expansions during DNA replication.
Answer: True
Anticipation, characterized by worsening disease symptoms over generations, is often driven by repeat expansions, frequently due to mechanisms like strand slippage during DNA replication.
The huntingtin protein's primary role is to initiate DNA replication.
Answer: False
The huntingtin protein is involved in preventing apoptosis and repairing oxidative DNA damage, not initiating DNA replication.
The FMRP protein, deficient in Fragile X syndrome, is involved in DNA repair.
Answer: False
The FMRP protein, deficient in Fragile X syndrome, is an RNA-binding protein crucial for normal brain development, not DNA repair.
Which disease is caused by an expansion of the CAG trinucleotide repeat in the huntingtin gene?
Answer: Huntington's disease
Huntington's disease is caused by an expansion of the CAG trinucleotide repeat in the huntingtin gene.
The expansion of a CCG trinucleotide repeat in the FMR1 gene is the genetic cause of which disorder?
Answer: Fragile X syndrome
The expansion of a CCG trinucleotide repeat in the FMR1 gene is the genetic cause of Fragile X syndrome.
What is the consequence of the GAA repeat expansion in the frataxin gene associated with Friedreich's Ataxia?
Answer: Silencing of the frataxin gene's first intron
The GAA repeat expansion in Friedreich's Ataxia leads to the silencing of the frataxin gene's first intron, causing frataxin deficiency.
Myotonic dystrophy type 2 (DM2) is linked to an expansion of which repeat sequence?
Answer: CCTG
Myotonic dystrophy type 2 (DM2) is linked to an expansion of the CCTG repeat sequence in the ZNF9 gene.
Which repeat sequence expansion is implicated in both Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD)?
Answer: GGGGCC
A GGGGCC repeat expansion in the C9orf72 gene is implicated in both Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD).
The phenomenon of 'anticipation' in diseases caused by repeat expansions refers to:
Answer: Increasingly severe symptoms over successive generations.
Anticipation refers to the phenomenon where diseases caused by repeat expansions become more severe in successive generations.
What is the function of the FMRP protein, whose absence causes Fragile X syndrome?
Answer: RNA binding and regulation of brain development
The FMRP protein is an RNA-binding protein crucial for normal brain development; its absence causes Fragile X syndrome.
Which of the following is a disease caused by a trinucleotide repeat expansion?
Answer: Spinocerebellar ataxia
Spinocerebellar ataxia is one of several diseases caused by trinucleotide repeat expansions.
Transposable elements can contribute to evolutionary innovation through a process called TE exaptation.
Answer: True
Transposable elements can contribute to evolutionary innovation through TE exaptation, where host organisms adapt TEs for new functions.
Repeat sequences may have influenced the evolution of eukaryotes by limiting lateral gene transfer in prokaryotes.
Answer: True
It is proposed that repeat sequences in prokaryotes limited lateral gene transfer and homologous recombination, potentially favoring the evolution of eukaryotes.
What is a potential beneficial role of transposable elements in evolution?
Answer: TE exaptation for new functions
Transposable elements can contribute to evolutionary innovation through TE exaptation, where they are repurposed for new functions.
How can repeat sequences contribute to genome evolution?
Answer: By providing raw material for genetic variation.
Repeat sequences contribute to genome evolution by providing raw material for genetic variation, influencing gene regulation, and enabling genome rearrangements.
Short reads from modern DNA sequencing technologies easily resolve complex repetitive DNA regions.
Answer: False
Short reads from modern sequencing technologies often make it difficult to accurately resolve and assemble complex repetitive DNA regions.
What challenge do repetitive DNA sequences pose for next-generation sequencing techniques?
Answer: Short reads make accurate assembly difficult.
Repetitive DNA sequences present challenges for next-generation sequencing because short reads make accurate assembly difficult.